Parking control devices are well known. A ticket is generally used as the storage medium upon which is recorded the authorization to park after payment of the parking fee, or which authorizes long-term parking. After the reading device has read an authorization recorded on the storage medium and a sensor at the parking stand has detected the presence of a vehicle, the parking gate mechanism is activated and the parking gate is opened accordingly. Another sensor is provided at the parking gate to prevent the gate arm from closing when a vehicle is beneath it.
Nowadays, induction loops laid in the pavement are usually used to detect the presence of a vehicle at the parking stand or beneath the parking gate. However, the installation of such induction loops involves a considerable outlay. Induction loops are also susceptible to damage, e.g. from shocks, or, as an example, should moisture penetrate through cracks in the pavement. Moreover, they are sensitive to environmental influences. In this way, temperature fluctuations can lead to a change in inductance and water on the roadway can lead to erroneous detection and opening of the gate arm. Additionally, the adjustment of sensors with induction loops is difficult, if not impossible, for metal-reinforced pavements. Induction loops can also be manipulated by metallic objects that simulate a vehicle.
The use of geomagnetic field sensors for the detection of flowing traffic and for the recognition of authorized access to parking areas, as well as the monitoring of entries and exits, is well known. This involves measuring deviations from the earth's natural geomagnetic field by the use of ferromagnetic bodies. The geomagnetic field sensors can be installed in or alongside the roadway, or overhead (U.S. Pat. No. 5,880,682, EP 1193662 A1).
The purpose of the invention is to configure the well-known parking gates more economically and reliably.
According to the invention, this result is attained by favorable configurations of the device disclosed herein.